Comment 1 for bug 1233500

There are several different places in the code where it might be appropriate to check for Block ownership. BlockInstance->instance_config_store() is one possibility (though it could be overridden by child blocks).

We check View ownership in blocks.php, so it might make sense to check the block ownership there as well.

Or, in View->process_changes(), before we set $this->blockinstance_currently_being_configured, it might make sense to verify at that point that the block ID is a block that actually belongs to this view.